The present invention generally relates to ladder accessories, and it is specifically directed to devices for easily mounting to the lower ends of the rails of a rigid ladder in order to prevent the ladder from sliding along any of a variety of types of ground surfaces and making the ladder unstable while it is leaning against a vertically extending support structure and its rungs are bearing the weight of a user.
There are a variety of devices, in the prior art, designed to better anchor a rigid ladder to the ground and prevent the lower end of a ladder from sliding along the ground while in use. These prior art non-slip devices generally fall within two categories that are distinguishable from one another by how the devices are to be attached to ladder rails. In one such category are non-slip devices that are to be securely attached to ladder rails by use of a mechanical fastener pin, screw, nut & bolt, etc.), and in the other category are non-slip devices to which ladders can be safely mounted by virtue of gravity and/or friction fitting.
One example falling within the first category is found in U.S. Patent Application Publication No. 2012/0199416 to Hopkins et al. Hopkins discloses a ladder stabilizing apparatus that principally features a base plate having an attached horizontal shaft that is elevated from the base plate. Ladder leg retainers are pivotally attached to that shaft by rotary bearing, and these leg retainers are each described as being an adjustable channel that forms a three-sided clamp that is locked into place around a ladder rail by a releasable fastener such as a bolt and wingnut assembly. The pivotability of the Hopkins leg retainers accommodates a range of ladder lean angles that a user might prefer, but the configuration of the apparatus ostensibly prevents the base plate from rotating more than 90 degrees when the apparatus is attached to a ladder. Thus, the base plate has definitive top and bottom surfaces, where only the bottom surface engages the ground. Notwithstanding the suggestion that an automobile be placed upon a portion of the base plate in order to anchor it to the ground, it is suggested that the bottom surface could be a friction-enhancing or non-slip surface and is further suggested that the base plate may feature apertures through which stakes or nails could be inserted in order to fasten the apparatus directly to the ground or other support surface.
One consequence of the aforementioned inability to completely invert the Hopkins base plate is that only one of its faces can function as a ground-touching surface. So, unless removable surfaces can be attached to that bottom face, it will always have the same topography and friction characteristics—which, invariably, will not be optimum for every conceivable ground or floor surface that a ladder may be used upon. Furthermore, even if extraneous surfaces can be removably attached to the bottom face of the base plate, the act of installing and substituting them can be tedious. It may be similarly tedious to have to insert spikes through holes within the base plate, for example, to provide the type of slide prevention that the base plate, alone, might experience if its bottom face was a spiked surface. Of course, these deficiencies exist for any base surface that is one-sided, in terms of its ground engagement function, because one particular surface topography and material will not be effective in preventing slippage along every ground and floor surface. Therefore, a ladder attachment that features multiple ground-engaging surfaces that have distinct topographies and are easily reversible may be more desirable.
To wit, as another example of a slip-inhibiting apparatus that is attached to the base of a ladder using mechanical fastening means, U.S. Pat. No. 2,623,679 to Agombar discloses a non-slip ladder base that features a pair of non-slip members that are each to be bolted to a ladder rail. Each such Agombar non-slip member is pivotable between positions in which either a single spike is downward facing to engage the ground or a frictional shoe is downward facing to do so. This configuration enables a user to select a ground engagement surface that is more effective in prevent sliding along the attendant ground surface. Furthermore, the two non-slip members are rigidly connected together by a transverse tube so that they pivot in unison. This eliminates the type of instability that might otherwise be experienced if the non-slip members were able to move independently while they are each affixed to a ladder rail.
A drawback of the Agombar assembly, however, is that its configuration necessarily limits the functional surface sizes of the alternative spiked and frictional surfaces. More specifically, the assembly configuration is such that, if the respective ground engagement surface areas of the non-slip members were expansive in longitudinal dimensions (i.e., in directions transverse to the direction of ladder rungs), the non-slip members might be unable to pivot between the two ground engagement surfaces being in their opposing down positions (due to the ladder interfering with the pivot path of the surfaces). And if those ground engagement surface areas were laterally expansive enough to cover a swath of ground space extending the entire distance between the ladder rails, the upward facing surfaces (those not in the ground-engaging position at a given moment) might obstruct the user's foot access to the lowest one or two ladder rungs and, thereby, pose a significant use hazard. Similar configuration-imposed size limitations on ground engagement surfaces are characteristic of other prior art non-slip attachments that are to be mechanically fastened to a ladder and are pivotable between alternate ground engagement surfaces.
Consequently, it may be desirable to employ a ladder slip-inhibiting apparatus that is not to be mechanically fastened to the ladder and, instead, features a base element that can be freely pivoted or flipped between different types of ground engagements. Such an apparatus is found in U.S. Patent Application Publication No. 2009/0200110 to Esselborn. More specifically, Esselborn discloses a generally planar anti-slip platform that has abutments—either in the form of recesses within a face of the platform or in the form of protrusions extending up from the face of the platform—which the ends of ladder rails will press against and will, thereby, prevent the ladder from sliding horizontally along the platform. Furthermore, in at least one embodiment, the Esselborn platform features different types of anti-slip surfaces along its opposing faces so that type of platform surface most suitable for preventing sliding along a particular ground or floor surface can be faced down in ground-contacting position.
Nevertheless, while the Esselborn apparatus provides multiple slip-inhibiting surfaces that are reversible without having to manipulate any mechanical fasteners, and while its configuration and engagement with a ladder in no way limits the functional surface area of the ground-engaging platform, it may still be deemed an inadequate solution for some. For example, if a user first positions one side of the platform on bottom, only to determine that its opposite side might be better suited to grip the attendant ground surface, the user will have to lift the ladder from the platform, turn over the platform and remount the ladder atop it. Typically, that sequence will require either (a) two persons (one person to lift and suspend the ladder while the other person flips over the platform) or (b) lifting the ladder, setting it down off of the platform, flipping over the platform and then re-placing the ladder back atop turned platform.
Consequently, the present inventors appreciate a need for a slip-inhibiting ladder base device that both (a) features two separate ground engaging surfaces and (b) allows a user to toggle between those two surfaces being in engagement with the ground or floor surface without the steps of mechanically unfastening and refastening the base device to the ladder or the steps of dismounting the ladder from and remounting the ladder to the base device. The present invention for a ladder base device substantially fulfills these needs.